by What is an electrolyte?
An electrolyte is a substance that produces an electrically conducting solution when dissolved in a polar solvent, such as water. Battery electrolytes provide ions that shuttle between the anode and cathode during the chemical reactions that produce electricity. Without electrolytes, batteries would not work. In batteries, electrolyte conducts the electric current by allowing ions to flow between the anode and cathode. The ions diffuse through the electrolyte solution, making possible redox chemical reactions between the electrodes that produce the electric current.
Types of electrolytes used in batteries
Different types of batteries use different Battery Electrolyte depending on their chemical composition and intended applications. Some common battery electrolytes include:
– Aqueous electrolytes: These are electrolytes that use water as the solvent. Common aqueous electrolytes include sulfuric acid in lead-acid batteries, potash and sodium hydroxide in alkaline batteries. Aqueous electrolytes offer higher conductivity but are more prone to drying out compared to other electrolytes.
– Gel polymer electrolytes: Also called solid polymer electrolytes, these don’t use a liquid solvent. The electrolyte is a gel or solid polymer impregnated with a lithium salt solution. Gel polymer electrolytes don’t leak but have lower conductivity than liquid electrolytes. They are used in lithium-ion polymer batteries.
– Liquid organic electrolytes: Organic solvents like ethylene carbonate or propylene carbonate are used instead of water. Common salts dissolved include lithium hexafluorophosphate or lithium tetrafluoroborate. Liquid organic electrolytes offer higher energy density than aqueous electrolytes while maintaining good conductivity. They are primarily used in lithium-ion batteries.
– Molten salt electrolytes: For high-temperature applications above the melting point of the salts, molten salts like sodium chloroaluminate or lithium chloride-potassium chloride eutectic mixtures are used. Molten salt batteries have high energy density and stability at elevated temperatures.
– Solid-state electrolytes: These are solid ion conductor materials like lithium phosphorus oxynitride (LiPON) or garnet-type lithium lanthanum zirconium oxide (LLZO) that conduct lithium ions at room temperature. Solid-state electrolytes could improve safety in future batteries by eliminating the flammability risks of liquid electrolytes. However, further improvement is still needed in ionic conductivity.
Role of electrolyte in a battery
Within a battery cell, the electrolyte plays a critical role in facilitating the electrochemical process that produces electricity. Here is a brief summary of how it works:
– The electrolyte contains ions that are free to flow between the anode and cathode electrodes. In a lithium-ion battery for example, the electrolyte contains lithium ions (Li+).
– During discharge, an oxidation reaction occurs at the anode which releases electrons. The released electrons flow through the external circuit, powering the device. Simultaneously, the lithium ions move from the anode through the electrolyte towards the cathode.
– At the cathode, a reduction reaction occurs where the lithium ions get inserted into the cathode material. The electrons from the external circuit also enter the cathode, allowing the reduction reaction to be completed.
– This movement of ions through the electrolyte and electrons through the external circuit forms the basis of the battery’s current generation capabilities. The electrolyte shuttles the charge-balancing ions between the electrodes as the battery charges and discharges.
– The electrolyte also acts as an electrical insulator between the anode and cathode, preventing an internal short circuit. If it didn’t exist, the redox reactions at the electrodes would happen spontaneously without generating electricity.
Challenges with battery electrolytes
While electrolytes are crucial for battery operation, they also present some challenges:
– Conductivity degradation: Over many charge-discharge cycles or due to high temperatures, the electrolyte’s conductivity can deteriorate leading to reduced battery performance and life. Additives are used to mitigate this effect.
– Flammability: Many organic electrolyte solvents used in lithium-ion batteries are highly flammable in their pure or concentrated state. Strict protocols are followed during battery manufacturing to minimize fire risks.
– Material interactions: Prolonged interactions between the electrolyte and electrode materials can cause unwanted side-reactions affecting cycling stability, impedance rise and capacity fade over time. Advanced additive packages are employed to suppress interactions.
– Temperature effects: Both very high and very low operating temperatures affect the electrolyte’s physico-chemical properties. Designing for stable performance across a wide thermal range is challenging.
– Cost and supply chain issues: Some electrolyte solvents and salts rely on imported raw materials. Ensuring cost-effective and reliable sourcing of electrolyte ingredients is important for large-scale battery deployments.
Outlook for battery electrolyte research
Designing better and safer electrolytes will continue to be a critical area of research to further progress battery technologies. Some promising approaches being explored include developing electrolytes with:
– Higher conductivity over a wider operating temperature window
– Improved interfacial stability against electrode materials
– Non-flammability for safety advantages
– Lower material and manufacturing costs
– Ability to operate efficiently inside solid-state batteries of the future
By addressing challenges related to conductivity, safety, cost and compatibility, researchers aim to engineer next-gen electrolytes that can help batteries achieve higher energy densities, longer lifespans and overall performance suitable for a wider range of applications. This remains an active area of innovation needed to support growing demand for advanced battery technologies worldwide.
*Note:
1. Source: Coherent Market Insights, Public Source, Desk Research
2. We have leveraged AI tools to mine information and compile it.
